1. Field
Although not so limited in its utility or scope, implementations of the present invention are particularly well suited for the deployment of sonobuoys, such as Light Weight Sound System (LWSS) buoys from aircraft and, more particularly, to apparatus for retrofitting existing single-buoy launch tubes in order to enable sequential, pneumatic deployment of multiple sonobuoys from the retrofitted launch tube.
2. Brief Description of Illustrative Environments and Related Art
Existing multi-sonobuoy launch systems are of generally two configurations. A first configuration is characterized by an array of launch tubes each of which launch tubes is dedicated to the storage and, when activated, ejection of a single sonobuoy. FIGS, A, B and C represent an existing array-type sonobuoy launcher A20 and a typical environment in which such a system is carried. More specifically, FIG. A shows an array-type sonobuoy launcher A20 carried in the side of an aircraft (i.e., a helicopter indicated partially in dashed lines). FIG. B shows the sonobuoy launcher A20 of FIG. A removed from the aircraft, enlarged and rotated to reveal the back side thereof. The sonobuoy launcher A20 includes a fixed array of launch-tube retainers A25 which, in the illustrative example, are cylindrically shaped hollow tubes. Each launch-tube retainer A25 is adapted to removably receive and retain a launch tube such as the launch tube A30 of FIG. C. Each launch tube A30 is adapted to store a single sonobuoy A400 and includes a breech end A32, a sonobuoy-ejection end A34 opposite the breech end A32 and a sonobuoy-retaining cavity A46. When a launch tube A30 is inserted into a launch-tube retainer A25, as indicated by the dashed arrow leading from FIG. C to FIG. B, a gas port A33 at the breech end A32 of the launch tube A30 is selectively connected into gas-tight fluid communication with a source of compressed gas A600 through a dedicated gas conduit A610 corresponding to the launch tube A30. In the example shown, each dedicated gas conduit A610 leads from a gas-distributing plenum A615 that directs gas fed to the plenum A615 from a gas main A620 leading from the gas source A600 to a selected launch tube A30. Gas fed to the beech end A32 of a launch tube A30 expels the sonobuoy A400 contained therein. Once a sonobuoy A400 has been launched, the location in the array-type sonobuoy launcher A20 is “re-loaded” by either (i) removing the “spent” launch tube A30 and inserting a fresh launch tube A30 containing a sonobuoy A400 into the corresponding launch-tube retainer A25 or (ii) inserting a fresh sonobuoy A400 into the launch tube A30 with the launch tube A30 still in place within the launch-tube retainer A25. The representative array-type sonobuoy launcher A20 described in conjunction with FIGS. A, B, and C is merely illustrative of array-type sonobuoy launchers in general and provides a single, non-limiting example of a sonobuoy launcher with which implementations of the invention disclosed and described below in the summary and detailed description may be caused to co-operate in a manner that will be appreciated upon examination of the aforementioned summary and detailed description.
A second general configuration of multi-sonobuoy launch system accommodates the storage and sequential launching of multiple sonobuoys from a single launch tube. Advances in related technological arts, including the miniaturization of electronic circuitry and data storage apparatus, for example, have enabled substantial reduction in the overall sizes of sonobuoys. With a reduction in the sizes of sonobuoys enabled, efforts have been undertaken to modify existing sonobuoy launchers to facilitate the sequential launch of multiple sonobuoys from a launch tube originally designed for the storage and launch of a single sonobuoy.
Various existing launch systems capable of sequentially launching multiple sonobuoys from a single launch tube involve the discharge of a distinct launch mechanism dedicated to the launch of each sonobuoy. The “launch mechanisms” employed have been of various types including reservoirs of compressed gas (e.g., CO2 cartridges) and small, impact-responsive explosive charges, for example. In some cases, a launch mechanism is situated in proximity to the sonobuoy to which it corresponds and activation mechanisms (e.g., electrical circuitry and an electrically-activated squib) are routed to it. In alternative examples, launch mechanisms are situated in relative proximity to one another (e.g., at the breech end of the launch tube) and a distinct gas-flow channel channels the gas generated upon the discharge of a launch mechanism to the rear of the sonobuoy to which that launch mechanism corresponds.
One existing multi-sonobuoy sequential launch system includes a launch tube that connects into a pneumatic air supply port on an aircraft (or other vehicle) to supply pressurized gas (i.e., air) through an opening at the breech end of the launch tube. Although this system harnesses the onboard air supply and obviates electrical activation circuitry, for example, it utilizes the onboard air supply only indirectly in order to activate independent discharge mechanisms. More specifically, the launch tube includes a control module at the breech end and a plurality of distinct gas-flow channels. The control module includes a plenum chamber that is in fluid communication with the onboard air supply. Each gas-flow channel leads from the control module to a unique location along the length of the launch tube and has a distal end, opposite the control module end, in fluid communication with a section of the launch tube situated to the rear of a sonobuoy stored in the launch tube. At the plenum chamber, an aperture corresponding to each gas-flow channel is initially plugged by a firing pin held in place by a shear pin. Each shear pin is characterized by a unique fault that causes it to fail under a predetermined load. The firing order is determined by the strength of the shear pins from weakest to strongest so that, for example, the weakest shear pin retains the firing pin plugging the channel leading to the forwardmost stored sonobuoy and the strongest shear pin retains the firing pin plugging the channel leading to the last sonobuoy to be launched. When a pneumatic pulse is fed into the plenum chamber from the onboard air supply, the weakest remaining shear pin fails and the firing pin retained thereby is forcibly driven into an impact-responsive squib situated alongside a gas-generating cartridge forward of the firing pin in the gas-flow channel. As the firing pin moves forward in the gas-flow channel, a spring-loaded cap closes off the gas-flow channel at the breech end. The gas discharged from the gas-generating cartridge travels down the gas-flow channel and forces the corresponding stored sonobuoy out of the launch tube. Subsequent pneumatic pulses cause failure of the remaining shear pins and the process is repeated until the supply of stored sonobuoys is exhausted.
Although single-tube, multi-sonobuoy launch systems are not entirely unprecedented, it will be appreciated that those systems utilizing an expendable launch mechanism (e.g., a gas-generating cartridge) corresponding to each sonobuoy to be launched are somewhat cumbersome and, if they are not to be disposed of, have associated with them a refitting expense. For instance, in the latter example described in the preceding paragraph, firing pins must be removed and shear pins and gas-generating cartridges must be replaced or refilled in order to render the sonobuoy launcher prepared for reuse.
Accordingly, there exists a need for a sonobuoy launch system that, in various implementations, facilitates relatively simple retrofitting of an existing, single-sonobuoy launcher system to enable the sequential launch of multiple sonobuoys from a single tube and that is, furthermore, readily reusable and relatively inexpensive and simple to recondition for use.